This longitudinal study investigates the role of the family in drug use by normal adolescents, both independently and relative to the influence of peers. A two-wave panel survey was carried out in Fall 1971 and Spring 1972 on a random sample of 8,206 New York State high school students, drawn from 18 schools throughout the state. At both times, structured, self-administered questionnaires were given to high school students in a classroom situation and self-administered questionnaires were mailed to their patients, alternately mothers and fathers. In five schools, data were also collected on the student's best schoolfriend. Interviews were carried out with a small number of the students who dropped out of school after the first wave of data collection and with their parents. A third wave of data collection was carried out on the 1972 senior class. Cross-sectional and longitudinal analyses are based on matched dyads of adolescents and parents, and triads of adolescents, best-schoolfriend and parent. The family and peer contexts and processes which are correlated with and which precede certain patterns of drug use are investigated along with changes in parental attitudes which result from different patterns of adolescent drug use. Family influences are studied in relation to drug behavior of the adolescent's best friend and other students in the school.